File Systems in AIX

AIX supports the following file systems:

• JFS

  Journaled File System (JFS) uses journals to keep structure integrity.

• JFS2

  Enhanced Journaled File System (JFS2) is the enhanced JFS. JFS2 is larger than JFS and has higher performance. JFS2 also stores larger files than JFS.

• NFS

  Network File System (NFS) is a distributed file system that allows users to access files and directories on remote PCs the same as on local PCs.

• CDRFS

  CD-ROM File System (CDRFS) allows access to CD-ROM contents from common file system interfaces.

In traditional UNIX operating systems, files may be damaged after a system fault, particularly the files that are constantly updated. AIX uses the following mechanism to address this issue:

When the contents of a file change, AIX records the structure change of the file to a database log before updating the file contents. The log used for recording file structure (metadata) changes is called a JFS log. After an accident such as a file system breakdown, AIX uses the JFS log to recover the file system.

JFS and JFS2 are the most widely applied file systems in common applications. Figure 2-1 compares the two file systems.

Figure 2-1 Comparison between JFS2 and JFS

For more information, see official IBM documents.

AIX 5.1, 5.2, and 5.3 support both 32-bit and 64-bit kernels. AIX6.1 and later versions support only 64-bit kernels. The maximum JFS2 file system size and maximum JFS2 file size vary with the AIX kernel. For details, see Figure 2-2.

Figure 2-2 JFS2 size limits in 32-bit and 64-bit kernel AIX operating systems

For more information, see official IBM documents.